1. Field of the Invention
The present invention relates to a system including a communication unit, a portable terminal communicating data with the communication unit, and an authentication unit ensuring security of communication between the communication unit and the portable terminal. More particularly, the present invention relates to a technique with which data communication can be implemented with ensured security even if a communication unit does not hold in advance information of a portable terminal when radio communication is established between the communication unit and the portable terminal.
2. Description of the Background Art
With the development of networks such as the Internet in recent days, data is communicated among a variety of devices. The data communicated in such a manner includes personal information which should not be leaked to a third party from the viewpoint of privacy protection. In order to avoid leakage of such personal information, it is necessary to establish data communication with a specified party.
Japanese Patent Laying-Open No. 10-336345 discloses a method of authenticating a caller with a high security level. The method of authentication disclosed therein authenticates a caller of a portable phone requesting access via an access point to an information provider unit connected to a network. This method for authenticating the caller includes the following steps: a portable phone requests line connection to an information provider unit via a controller at the access point; the portable phone transmits a telephone number thereof to the information provider unit via the controller after the line is connected; the information provider unit authenticates whether or not the received telephone number is the number of the contracted user registered in advance; the information provider unit transmits an authentication result to the controller; and the controller forms a logic path between the portable phone and the information provider unit based on the authentication.
According to the authentication method, authentication of the caller requesting a communication access to the network is carried out based on the telephone number of the portable phone. Therefore, compared to the authentication method based on a user ID and a password, security level of authentication of the caller is significantly improved, because the telephone number notified through “caller ID display” of the portable phone can be used for authentication.
In the authentication method disclosed in the publication, however, the telephone number of the contracted user should be registered in advance in the information provider unit. In addition, the controller at the access point has to be able to communicate with the information provider unit. In other words, in an attempt to implement the authentication method disclosed in the publication described above, it is necessary that the controller at the access point is connected to the information provider unit authenticating if the caller is the contracted user, and that a telephone number of a portable phone or PDA (Personal Digital Assistant) is registered in advance as authentication information in the information provider unit. Recently, a portable phone or a PDA mounted with a short-range radio communication device such as Bluetooth is used to receive a variety of information from controllers installed at access points in a city. In such a case, it is difficult to register in advance information for authenticating a portable phone or a PDA in all controllers.